Prompt
Select lock types based on access patterns - prefer RWLock over Mutex for read-heavy operations to enable concurrent reads while allowing exclusive write access. Minimize lock scope to essential operations and avoid holding locks across await points in async code.
// AVOID: Using Mutex for read-heavy operations
type MetaData = Mutex<HashMap<String, HashMap<String, ParquetFile>>>;
// BETTER: Using RWLock for read-heavy operations
type MetaData = RwLock<HashMap<String, HashMap<String, ParquetFile>>>;
// AVOID: Taking lock before doing computation
async fn persist_parquet_file(&self) -> Result<(), Error> {
// Lock held during entire function including computation
let mut meta_data_lock = self.meta_data.write();
// Long computation while holding lock
let result = compute_expensive_result().await?;
// Update metadata
}
// BETTER: Taking lock only when needed
async fn persist_parquet_file(&self) -> Result<(), Error> {
// Do computation without holding lock
let result = compute_expensive_result().await?;
// Only take lock when updating shared state
let mut meta_data_lock = self.meta_data.write();
// Update metadata with minimal lock time
}
For high-contention scenarios, consider specialized concurrent data structures like DashMap that distribute lock contention. Keep related data under the same lock to ensure atomic updates across multiple data structures.